Electrical outlet for three-prong locking plugs



Febo 3, 1959 2 Sheets-Sheet 1 FIG-l N I as w ,550W/Ai s I4 v g: |2 .7 fllI-//////Z FIG-2 INVENTOR. FIG 3 Wilbur R. Smith w. R. sMlTH 2,872,654

ELECTRICAL OUTLET Toa THREE-BRONS LOCKING PLUGS Filed Aug. 4, 1955 Feb. 3, 1959 w. R. SMITH 2,872,654

ELECTRICAL OUTLET FOR THREE-PRONG LOCKING PLUGS File'd Aug. 4, 1955 2 Sheets-Sheet 2 l l' I6 l 3| la 2o 29 26 FIG-5 lNvENToR. Wilbur R. Smith nited States Patent O ELECTRICAL OUTLET FOR THREE-PRONG LOCKING PLUGS l This invention is an electrical outlet adapted to be used with an electrical plug. It is one object of the invention to provide an outlet of such construction that the third or ground prong of an electrical plug may be received and grounded therethrough.

Another object of the invention lies in the provision of an electrical outlet which has a rotatable cylinder adapted to receive the prongs of a plug and connect the ground or third prong of the plug to a grounded system.

Another object of the invention lies in the improvement of an electrical outlet having rotatable cylinders adapted to receive and llock the prongs of a plug therein which is specifically designed to receive a three-prong plug and electrically connect the third or ground plug to the ground of the electrical system.

The foregoing and other lobjects will become apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts:

Figure 1 is a front elevation showing the face of the wall outlet embodying the present invention and having a cover plate;

Figure 2 is a vertical enlarged cross section on a plane substantially as indicated at line 2-2 of Figure 1;

Figure 3 is a rear view partially in cross section `substantially at the planes indicated by lines 3--3 of Figure 2; and

Figure 4 is a fragmentary vertical cross section taken substantially on the plane indicated by line 4 4 of Figure 2; and

Figure 5 is a lateral cross section taken substantially on the plane indicated by line 5-5 of Figure 3.

Referring now with greater particularity to the drawing, I have shown my improved outlet as having a body formed of insulation and provided with a pair of cavities 11 in which are disposed a pair'of revolvable cylinders 12. The body 10 is also provided with a metallic conductive frame 13 having upper and lower ears 14 of conventional construction and adapted to releasably secure the electrical outlet into a conventional metal outlet box (not shown).

The vbody 10 is also provided with a rear cap 15 which has a marginal edge flange 16 adapted to associate with the body 10 and positionthe cap thereon` The cap 15 is also provided with bosses 17 which are disposed at the axis of the cylinders 12. A conventional cover plate 18 is releasablysecured to the frame 13 by means of the bolt 19.

As seen in Figure l, the cylinders 12 are'provided with the conventional electrical prong sockets 20 and in addition are provided with the third socket 21 which provides means for receiving the ground or third prong 22 of the electrical plug 23 having in addition the two conventional prongs 24. A contact strip 25 is disposed in each of the sockets 21 of cylinders l2 and has a right angle por tion 26 which terminates at the axis of its respective cylinder.

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The cylinders 12 are each provided with a bore 27 at its axis through which a journal pin 28 extends and the head 29 ofthe journal pin rests upon theright angle portion' 26 of thevcontact strips 25 while the body of the journal pin 28 extends therethrough, in this manner providing an electrical connection between the conductive journal pin 28 and its respective contact strip 25, and yet permitting rotation of the cylinder 12.

A fastener strip 30 is disposed on the outer face. 15 of the cap 15 and the ends of the journal pins 28 are threadedly engaged into threaded apertures in the strip 30 to secure the cap in place and also to anchor the cylinders 27 against movement out of the cavities 11 forwardly.

The cylinders 12 are prevented from removal rearwardly from the body 10 by the electrical contacts 31 which are electrically associated with the strips 32 adapted to associate with the prongs 24.

In Figure 4 it will be noted that plungers 35 are pro-- vided in the walls of the cylinders 12 and the cavities 11 are elliptical in shapev to provide means for locking the prongs 24 of the plug 23 in the cylinders 12 when desired. This is more particularly disclosed and claimed in my previous Patent No. 2,704,831 of Mar-ch 22, 1955.

The present invention lies in the improvement adapting that structure to the three-prong plug 23 torpermt grounding of the electrical utility and also locking of the prongs 24 therein.

It will be noted that the fastening bolt 36 (Figure 2) is swedged at its head 37 to secure the frame 13 to the body 10 and is provided with an internally threaded opening 38 adapted to receive the cover plate fastening bolt 19. The bolt 36 is threadedly engaged into the fastening strip 30 and thereby unites the complete unit for fastening in a conventional outlet box and also completes electrical connection between the frame 13 and the strip 25.

Obviously when the frame 13 is electrically connected to the outlet box (which is conventionally grounded) vthe contact strips 25 will be grounded through the electrical connections inter-connecting the journal pins 28 the fastener strip 30, the fastening bolt 36 and the frame 13.

Having thus described my invention, I claim:

1. An electrical outlet comprising a Ibody having a cavity; a revolvable cylinder in said cavity; a conductive frame supporting said body and adapted to be physically and electrically connected to an outlet box; said cylinder having at least three prong-receiving sockets therein; each said socket having a contact strip for electrically contacting the prong of a mating electric plug; locking means for alternately gripping and releasingthe prongs of a plug disposed in selected ones of said sockets upon rotation of said cylinder; means for electrically connecting certain of said contact strips to an electrical system; another said contact strip extending to and terminating at the axis of said cylinder; a rear insulating cap on said body; a conductive fastening strip outside of said cap; said cylinder having a bore at its axis; a journal pin extending through said bore l and cap and releasably secured in said fastening strip and electrically connected to said contact strip at the axis of said cylinder; and a conductive fastening bolt secured to said frame and extending through said body and cap and releasably secured to said fastening strip, whereby said contact strip is electrically connected to said frame.

2. An electric outlet comprising a body having a cavity; a revolvable cylinder in said cavity; a conductive frame supporting said body and adapted to be physically and electrically connected to an outlet box; said cylinder having three prong-receiving sockets therein, two of which contain contact strips for electrically contacting two prongs of a three-prong electric plug, the third said socket having a contact strip therein for electrically contacting the third prong of a three-prong plug and extending to and terminating at the axis of said cylinder; means for contricalconductor'extending through saidcylinder'at-its axisy and electrically 'connected toithe` Contact stripv Aterminating at-the axisof thecylinder; and means electrically connecting saidl conductor` tothe conductive framewhereby'f said last named contact strip is electrically connected to said frame;

References Cited in the le of this patent UNITED STATES PATENTS Hollander July 8, 1941 Smith Mar. 22, 1955 

